# Copyright 2024 Superlinked, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import threading

from beartype.typing import Any


class SingletonMeta(type):
    _instances: dict[Any, Any] = {}
    _lock = threading.Lock()

    def __call__(cls, *args: Any, **kwargs: Any) -> Any:
        with cls._lock:
            if cls not in cls._instances:
                cls._instances[cls] = super().__call__(*args, **kwargs)
        return cls._instances[cls]
